Rail tickets used for 3-day trip in Paris

Hi Ben,
My plan is as follows:
Day 1: Arrive at Charles de Gaulle Airport around 3 pm. Transfer to Paris center.
Day 2: Visit Chateau de Verssailles and Louve Museum.
Day 3: Go to Luxemburg by TGV, then go to Lyon by TGV.
What is the best rail ticket should I buy (for couple)?
Thank you,
Stephanie